1. Field of the Invention
The present invention relates to detent structure of the type which captures a detent member against a bias spring in a recess. The invention also relates to a method and apparatus for forming the detent structure by deforming material around the open end of the recess to define a retaining lip.
2. Description of the Prior Art
It is known to retain a detent member, such as a detent ball, in a recess against a bias spring by means of deforming the material around the outer end of the recess inwardly to form a retaining lip which captures the detent ball in the recess. Typically this has been accomplished by the use of an embossing tool which is driven axially into the recess, the tool typically having a flat annular embossing surface which extends around the open end of the recess and pushes the material around the open end of the recess downwardly, displacing it radially inwardly to form the retaining lip. Such detents are typically used in tools such as drive squares for sockets, as in ratchet wrenches and the like.
It has been found that the detent-retaining lip or emboss formed by such prior art embossing techniques has been the source of a relativly high percentage of failures in tools such as drive squares and the like, in that cracks have tended to originate in the retaining lip. It is theorized that this is because of the particular concentration of stress forces in the retaining lip caused by the embossing process and, in particular, by the shape of the embossing tool.